Brake shoe keylock



Oct. 17, 1939. F E-FE 2,176,724

BRAKE SHOE KEYLOGK Filed Oct. 21, 1958 IlIgg/EN R. m L wimp up BY AgATTO YSf Patented Oct. 17, 1939 PATENT OFFICE BRAKE SHOE KEYLOGKFrederic Schaefer, Pittsburgh, Pa. 7 I Application October 21, 1938,Serial No. 236,229

8 Claims.

This invention relates to railway car brake rigging, and moreparticularly to brake heads and shoes. p

Railway brake shoes aredetachably connected to brake heads by means ofkeys that extend downwardly through vertically spaced lugs projectingfrom the head. Each shoe is provided with a pair of horizontally spacedlugs in which the ends of a substantially vertical hardened metal strapare embedded, and they project between the brake head lugs. The keyextends between this strap and the shoe, whereby the shoe is attached tothe head. Various types of keys have been proposed which are locked inposition so that they will not accidentally permit the shoe to fall fromthe head. Nevertheless, a great many solid, onepiece, non-locking keysare still used, and such keys have a tendency to work upwardly out ofplace and occasionally release a brake shoe.

It is among the objects of this invention to provide means for looking abrake shoe key in position in a simple and inexpensive, yet effective,manner, and which is operative regardless of which end of the shoe isdown.

The preferred embodiment of the invention is illustrated in theaccompanying drawing in which Fig. 1 is a side view, partly broken away,of a brake head, shoe and key; Fig. 2 is a horizontal section taken onthe line 11-11 of Fig. 1; Fig. 3 is a vertical section taken on the lineIIIIII of Fig. 1; and Fig. 4 is an enlarged transverse section throughthe brake shoe strap.

Referring to Fig. 1 of the drawing, a brake head I is provided with apair of forwardly projecting vertically spaced lugs 2 provided with theusual passages 3 therethrough for receiving a brake shoe key 4. Thishead supports a brake shoe 6 which has a pair of horizontally spacedlugs l projecting rearwardly between the brake head lugs. As is theusual practice, the outer ends of the shoe lugs are connected by a crossmember or strap 8 of hardened steel, the ends of which are cast into thelugs (Fig. 3). The brake shoe key extends between this strap and theshoe whereby the shoe is detachably connected to the head.

Any type of key may be used, although this invention will generally havemore utility with solid one-piece keys than with multiple leaf wedgelock keys. A conventional one-piece key is shown in the drawing. Ittapers towards its lower end to form a wedge and is driven downwardlyacross strap 8 until the shoe is drawn up tightly against head lugs 2.

It is a feature of this invention that the head or shoe, or both, areprovided with means for tightly gripping the key its upward movementthat it is very unlikely that the key will work loose. Accordingly, theinner surface of the brake shoe strap is provided with a plurality ofprojections, preferably in the form of vertically spaced horizontalserrations ll that tend to dig into the adjoining surface of the key andprevent it from moving upwardly. To facilitate downward movement of thekey across the serrations and at the same time to increase theirresistance to upward movement of the key, the serrations that are ingripping engagement with the key should face downwardly; that is, theupper surface of each such serration is inclined but its lower surfaceis substantially perpendicular to the key (Fig. 4). As the key is bothtapered and curved away from strap 8, they tightly engage each otheronly for substantially the upper half of the strap. Due to this and theface that brake shoes are reversible so that either end may be at thetop, the serrations on the upper half of the strap face downwardly andthose on the lower half face upwardly, as shown in Fig. 4. Consequently,the key is tightly engaged by downwardly facing serrations regardless ofwhich end of the brake shoe is uppermost.

As a means of still further increasing resistance to upward movement ofthe key, or as an alternative means, one or both of brake head lugs 2may likewise have their inner surfaces provided with projections orhorizontal serrations for engaging the key. Ordinary cast brake headlugs are not hard enough to provide serrations of the desired hardness.Furthermore, it would be very difficult to cast the serrations into thelugs. Therefore, the body It of each lug is preferably provided with ahardened steel liner ll in one face of which the serrations ill havebeen cut (Figs. 1 and 2) This liner is cast onto a lug 2 when the headis cast, and preferably has laterally bent top and bottom portions thatextend into recesses in the top and bottom of the lug body to aid inpreventing the liner from being moved vertically by the brake shoe key.All of the serrations I8 face downwardly because the brake head is neverput on bottom side up.

According to the provisions of the patent statutes, I have explained theprinciple and construction of my invention and have illustrated anddescribed what I now consider to represent its best embodiments.However, I desire to have it understood that, within the scope of theappended claims, the invention may be practiced otherwise than asspecifically illustrated and described.

I claim:

so as tooffer such resistance to 1. In combination, a brake head havinghollow lug members, a brake shoe provided with a strap member, and asmooth-surface brake shoe key for locking the shoe to the head, theinner surface of at least one of said members being provided with aplurality of relatively sharp projections for frictionally engaging theadjoining surface of said key.

2. In combination, a brake head having hollow lug members, a brake shoeprovided with a strap member, and a smooth-surface brake shoe key forlocking the shoe to the head, at least one of said members beingprovided with a plurality of sub- ;stantially horizontal serrations forengaging the adjoining surface of said key.

3. A brake shoe strap provided on its inner surface with a plurality ofrelatively sharp projections for frictionally engaging and gripping asmooth-face brake shoe key.

4. A brake shoe strap provided on its inner surface with a plurality ofsubstantially horizontal serrations for engaging a smooth-face brakeshoe key.

5. A brake shoe strap provided on its inner surface with a plurality ofsubstantially horizontal serrations for engaging a brake shoe key, theserrations on the upper half of the strap facing downwardly, and thoseon the lower half of the strap facing upwardly.

6. A brake head having a pair of vertically spaced lugs provided withaligned passages for receiving a brake shoe key, the key-engagingsurface of at least one of said lugs being provided with a plurality ofrelatively sharp projections for gripping the adjoining surface of thekey.

'7. A brake head having a pair of vertically spaced lugs provided withaligned passages for receiving a brake shoe key, the key-engagingsurface of at least one of said lugs being provided with a plurality ofsubstantially horizontal serrations.

8. A brake head having a pair of vertically spaced lugs provided withaligned passages for receiving a brake shoe key, at least one of saidlugs comprising a body member and a key-engaging hardened metal liner,said liner being provided with a plurality of substantially horizontalserrations.

. FREDERIC SCHAEFER.

